I just bought an ea8100 v1 router (expensive in my country)
At first, I put openwrt on it from the web environment, but the router booted on the original OEM firmware after 3 attempts to reboot, as a result, I connected to the router through the serial port and installed this firmware on both A/B partitions.
https://downloads.openwrt.org/releases/23.05.2/targets/ramips/mt7621/openwrt-23.05.2-ramips-mt7621-linksys_ea8100-v1-squashfs-factory.bin
I installed it and after that the router fell into an infinite restart loop and nothing would boot
I was trying to understand the problem and fix it when I came to your post in the forum and mistakenly entered the two commands you entered.
I didn't know that this was irreversible and I thought that I could restore the router to normal by just reinstalling the OEM, but after turning the router off and on, nothing booted and the serial connection did not show anything.
Now I did not know the destructive effect of these two commands and how I should communicate with the router so that I can return the router to normal mode.
I found these links which are almost related to my problem but I don't understand what to do
https://forum.openwrt.org/t/creating-a-ubifs-for-nand-kernel-cmdline-arguments